It is unlawful for any person to dust, seed or spray any form of plant life from an aircraft over the city or to practice or exercise aerial maneuvers incident to such operation of dusting, seeding or spraying within the city. A permit waiving the provisions of this section may be approved by the police chief, city health officer and airport superintendent or, in the event of an emergency due to delay in the interest of public welfare, approval by the city health officer. (Prior code § 4.01.009)